A standard drill chuck has a guide body that may form the core of the chuck or that may be formed as a tightening sleeve and that is itself formed with guides inclined to the chuck axis. Respective jaws are axially slidable in these guides and have teeth that mesh with a screwthread of an adjustment body that itself may either be the core of the chuck or a sleeve. Both these bodies are axially fixed on the drill spindle. The guide body is typically rotationally fixed on the drill spindle while the adjustment body is rotatable thereon so that relative rotation of these two bodies in one direction moves the jaws axially forward and radially inward toward one another and opposite relative rotation moves them axially back and radially apart. Thus it is possible by rotation of this adjustment body to clamp a tool (or workpiece) in the jaws and by opposite rotation to release this tool (or workpiece).
German patent document 3,727,147 whose U.S. equivalent is U.S. Pat. No. 3,836,563 describes a system wherein the threaded adjustment body is the core of the chuck and has a frustoconical surface formed with the screwthread that serves to displace the jaws. The guide body is a sleeve surrounding the adjustment body and rotationally fixed on the spindle. A locking ring is provided on the chuck and has teeth urged by a spring into axial engagement with teeth of the adjustment body to prevent it from loosening or from tightening excessively, as the screwthread is of such a hand that the torque exerted via the jaws on the chuck parts tightens the chuck. This locking ring is movable between a pair of end positions defined by a pin set in a recess of the adjustment sleeve.
In German patent document 3,808,155 another arrangement is known wherein the guide body is surrounded by an adjustment sleeve having an internal screwthread and itself rotationally and axially fixed on the drill spindle. This arrangement also has a locking ring between the guide body and the adjustment sleeve for limiting tightening action.
Both systems use a one-piece drill spindle that cannot move axially or rotationally relative to the screwthreads. Thus this threaded body serves to transmit axial force, the hammering, to the jaws via the screwthread on this body and the teeth on the jaws. The result is an extremely effective self-tightening action that in fact can lead to the chuck getting so tight that it becomes very difficult or even impossible to loosen it and free the tool (or workpiece).